The subfamily Bambusoideae (of the family Poaceae), comprises both woody and herbaceous bamboos. At present roughly 120 genera of temperate and tropical woody bamboos are recognized. Bamboos are versatile plants with many different applications. It has been estimated that approximately 2.2 billion people worldwide use bamboo to some extent, and in 1985 the global revenue attributable to bamboo was estimated around U.S. $4.5 billion. The market for bamboo is also expanding. Bamboo shoots are a staple of Asian cuisine, and bamboo is found in a number of products including toothpicks, brooms, poles for viticulture and arboriculture, landscaping materials, parquet flooring, laminate materials, furniture, handicrafts and other household items. In addition, bamboo is becoming an important source of textile material as a component of paper production and as a source of structural timber.
Bamboo is considered an environmentally friendly “green” product. One of the characteristics that gives bamboo its green reputation is its extremely rapid growth rate. Bamboo is the fastest growing woody plant in the world, achieving growth rates of well over three feet per day. It achieves this rate of growth in part because of its rhizome system, which is capable of providing a great deal of energy toward shoot growth.
Despite bamboo's rapid growth rate, it has other characteristics that make it a difficult crop to manage. Perhaps the greatest difficulty comes from the fact that many commercially important bamboos only flower at intervals of as long as 60-130 years. Compounding the difficulties of this long flowering cycle is the fact that many bamboos exhibit mass (or gregarious) flowering, with all plants in the population flowering simultaneously. For example, Phyllostachys bambusoides flowers at an interval of 130 years, and in this species all plants of the same stock flower at the same time, regardless of differences in geographic locations or climatic conditions. After flowering, the bamboo dies.
Bamboo's lengthy flowering interval and propensity for mass flowering makes it very difficult to obtain seeds for propagation. Compounding this problem is the fact that bamboo seeds, even when they are available, remain viable for no more than 3-6 months.
As a result of these difficulties with the propagation of bamboo by seed, bamboo typically is propagated by asexual techniques such as clump division and cutting. These asexual propagation techniques, however, are insufficient to meet projected world demand because both their capacity to produce mass scale production, and their practical efficiency, are too low. In addition many asexual propagation methods have the downside of failing to eliminate pathogens present in the parent plants.
A method to achieve large scale production of bamboo is highly desirable. Micropropagation (also known as tissue culturing with the terms used interchangeably herein), is an excellent method to achieve this aim.
Micropropagation is not unlike growing plants from cuttings. However, unlike plants grown from cuttings, micropropagated plants are grown in vitro in sterile media. Typically, the media comprises agar, with the addition of various compounds such as nutrients, inorganic salts, growth regulators, sugars, vitamins and other compounds.
A benefit to tissue culturing plants is that the plants can be grown in a sterile environment so that they remain disease free. Other benefits include the ability to grow very large numbers of plants in a small space, the reduced water and nutrient needs of micropropagated plants, and the rapid multiplication of tissues that can in turn be used to yield more tissue culture material. Moreover micropropagation is very flexible and rapid upscaling is possible (within 1 year nearly one million plants can be produced from any genotype). Such short time frames and large numbers cannot be rivaled by any conventional method. Tissue culturing also provides for the production of high quality plants which are easy to transport and deliver.
Some papers have been published which address tissue culturing of bamboo. In practice, however (i.e., for large or mass scale propagation of bamboos), the methods described in these papers do not translate into commercially viable propagation systems.
The difficulties encountered in tissue culturing bamboo are high incidences of endogenous or surface contaminations and browning, factors related to dormancy or topophysis and hyperhydricity. The present disclosure provides media, systems and methods that overcome these difficulties allowing the commercial-scale asexual production of bamboo.